The present invention relates generally to techniques for treating hearing disorders in people. More particularly, the present invention relates to computer implemented methods for characterizing and treating tinnitus.
Tinnitus is commonly referred to as "ringing of the ear." It is a perceived sound that cannot be attributed to an external source. One cause of tinnitus, common in hearing loss, is believed to be damage to the hair cells of the cochlea responsible for reception of sound. As an example, damage can be to the hair cells responsible for reception in the 4 kHz to 8 kHz range. As a result, sound in this frequency range may not be transformed adequately into voltage potentials that can be conducted by neurons and processed by the central auditory system. In general, tinnitus will commonly occur at the lower frequency end of the malfunctioning range, or 4 kHz in the above example. Tinnitus can vary in intensity and, as an example, may be perceived as an intensity from 5 to 10 dB, although some tinnitus sufferers have reported a higher intensity level.
Most people have experienced tinnitus, for example, after hearing a traumatically loud noise or series of loud noises over time. The effects of tinnitus have been associated with hearing loss; approximately one third of elderly people experience the problem on a regular basis. Of greater concern is the one-half to one percent of people who are considered disabled by tinnitus. For these people, tinnitus impairs their ability to lead a normal and healthy lifestyle. As a result, numerous techniques have been used to reduce the effects of tinnitus.
In the past, surgical intervention and cutting of the auditory nerve was used to reduce the effects of tinnitus. Since the malfunction was once thought to be in the cochlea, which is part of the peripheral nervous system, the surgery aimed to remove the input to the central auditory system, and perception. Despite the rather severe side effect of total hearing loss, there were many people who preferred this to suffering from the effects of tinnitus. Unfortunately, in two to four weeks, the effects of tinnitus often returned. Thus, although tinnitus may be initiated by problems in the peripheral auditory system, it is no longer thought that tinnitus is maintained solely by the peripheral nervous system.
It has been suggested that there is an increase in activity in the primary auditory cortex when a person has tinnitus. The primary auditory cortex is part of the central auditory system, which is responsible for processing the inputs of the hearing system. Another indication that the maintenance of tinnitus is in the processing portion rather than in the peripheral nervous system is that a person with tinnitus cannot adapt to the ringing in the ears the way they can to a steady ambient 5 to 10 dB sound. For example, a person with tinnitus can adapt to or shut out the sounds of a fan in the room but cannot do the same for the tinnitus. Recent treatments have focused on this ability to adapt to ambient noise.
The use of a noise masker is one current method used to treat tinnitus by continually supplying a background noise having a constant intensity and drowning out the sound of the tinnitus. This method may be used for tinnitus sufferers who have difficulty falling asleep due the discomfort of the ringing noise. It is hoped in this case that the person is more tolerant of the masker-produced noise than of the constant ringing of the tinnitus and that the person can become accustomed to the masker-noise over time. Disadvantageously, this method requires the patient to tolerate background noise over the sound of the tinnitus. Further, the person must also sacrifice hearing ability at low intensities due to the interfering background noise. And finally, the person must also be open to wearing an external hearing aid.
Another recent method for treating tinnitus is through tinnitus retraining therapy. In this therapy, a masker is used to set a a noise intensity slightly lower than the intensity needed to block the perception of the tinnitus. The goal in this case is to have the person adapt to the intitial slight difference between the tinnitus and the noise provided by the masker. When the person no longer focuses on the tinnitus with this difference, the masker noise is turned down and the person must adapt to a slightly greater difference. This gradual resetting of intensity levels and building of tolerance levels is repeated until the person does not focus on the tinnitus even without the masker.
Although the prior art techniques may, if properly administered, help the person live with the tinnitus, there are disadvantages. Both techniques described force the person to wear a hearing device. They also both rely on the presumption that the person prefers the masker-noise. Both treatments may also compromise the ability to hear low intensities. More importantly, the attempts to remedy this problem have been based on training the person to adapt to, or become more tolerant of, the tinnitus and have not focused on the abnormality in the auditory cortex that maintains the tinnitus.
In view of the foregoing, there are desired improved techniques for characterizing and treating tinnitus.